Fourteen of the 19 suspects in the deadly shootout between two gangs in Muang district of Ubon Ratchathani early this month have been arrested.
Two gang members died in hospital and six others were treated for bullet wounds.
Pol Lt Gen Sompong Chingduang, assistant national police chief, on Tuesday described the gunfight between the rival gangs on the night of Aug 3 as "outrageous" and said those involved had no fear of or respect for the law.
He said deputy national police chief Pol Gen Suchart Teerasawat was overseeing the investigation.
Pol Lt Gen Sompong said Ubon Ratchathani Provincial Court had approved warrants for the arrest of 19 gang members. Fourteen had now been arrested. The last had surrendered on Tuesday. Police were hunting down the remaining five, he said.
Investigators were also examining weapons seized from those involved, said Pol Lt Gen Sompong, who is leading the investigation team.
Photos on social media earlier showed gang members carrying automatic assault weapons. Similar weapons were displayed by police at Tuesday's media briefing.
Pol Lt Gen Sompong said 70-80 people were being investigated in total. There could more warrants and more arrests.
Two rival gangs employed as guards at two pubs, the Phayayor and Ekkamai 487, near the Big C store in Muang district, arranged a meeting at a parking lot late on the night of Aug 3 to settle a dispute, but negotiations failed.
Witnesses told police they heard a noisy quarrel between the two groups of young men. It quickly escalated to violence with dozens of gunshots fired. Six members of the two gangs were treated for wounds and two others pronounced dead after being admitted to hospital.
Earlier, reports said two people were killed and five others wounded in the gunfight.
Police have also pressed charges against the owners of the two pubs for operating and modifying the premises without proper permits.